1. Field
The present invention relates generally to resettable circuit interrupting devices and systems and more particularly to a ground fault circuit interrupter (GFCI) device and receptacle having plug blocking means.
2. Description of the Related Art
Many electrical wiring devices have a line side, which is connectable to an electrical power supply, a load side which is connectable to one or more loads and at least one conductive path between the line and load sides. Electrical connections to wires supplying electrical power or wires conducting electricity to one or more loads can be at the line side and load side connections. The electrical wiring device industry has witnessed an increasing call for circuit breaking devices or systems which are designed to interrupt power to various loads, such as household appliances, consumer electrical products and branch circuits. In particular, electrical codes require electrical circuits in home bathrooms and kitchens to be equipped with ground fault circuit interrupters (GFCI). Presently available GFCI devices, such as the device described in commonly owned U.S. Pat. No. 4,595,894 (""894), use an electrically activated trip mechanism to mechanically break an electrical connection between the line side and the load side. Such devices are resettable after they are tripped by, for example, detection of a ground fault. In the device disclosed in the ""894 patent, the trip mechanism used to cause the mechanical breaking of the circuit (i.e., the conductive path between the line and load sides) includes a solenoid or trip coil. A test button is used to test the trip mechanism and circuitry is provided to sense faults. A reset button is provided to reset the electrical connection between the line and load sides.
However, instances may arise where an abnormal condition such as a lightning strike may result not only in a surge of electricity at the device which can cause a tripping of the device but can also disable the trip mechanism used to cause the mechanical breaking of the circuit. This can occur without the knowledge of the user. Under such circumstances an unknowing user, faced with a GFCI which has tripped, may press the reset button which, in turn, will cause the device with an inoperative trip mechanism to be reset without the ground fault protection being available.
Further, an open neutral condition, which is defined in Underwriters Laboratories (UL) Standard PAG 943A, may exist with the electrical wires supplying electrical power to such GFCI devices. If an open neutral condition exists with the neutral wire on the line (versus load) side of the GFCI device, an instance may arise where a current path is created from the phase (or hot) wire supplying power to the GFCI device through the load side of the device and a person to ground. In the event that an open neutral condition exists, a GFCI device which has tripped, may be reset even though the open neutral condition may remain.
Commonly owned U.S. Pat. No. 6,040,967, which is incorporated herein in its entirety by reference, describes a family of resettable circuit interrupting devices capable of locking out the reset portion of the device if the circuit interrupting portion is non-operational or if an open neutral condition exists. Circuit interrupting devices normally have a user accessible load side connection such as a GFCI protected receptacle in addition to line and load side connections such as binding screws. The user accessible load side connected receptacle can be used to connect an appliance such as a toaster or the like to electrical power supplied from the line side. The load side connection and the receptacle are typically electrically connected together. As noted, such devices are connected to external wiring so that line wires are connected to the line side connection and load side wires are connected to the load side connection. However, instances may occur where the circuit interrupting device is improperly connected to the external wires so that the load wires are connected to the line side connection and the line wires are connected to the load connection. This is known as reverse wiring. Such wiring is prevalent in new construction, where power is not yet provided to the residence branch circuits and the electrician has difficulty in distinguishing between the line side and load side conductors. In the event the circuit interrupting device is reverse wired, the user accessible load connection may not be protected, even if fault protection to the load side connection remains.
A resettable circuit interrupting device, such as a GFCI device, that includes reverse wiring protection, and optionally an independent trip portion and/or a reset lockout portion is disclosed in U.S. Pat. No. 6,246,558, (""558) assigned to the same assignee as this invention and incorporated herein by reference in its entirety. Patent ""558 utilizes bridge contacts located within the GFCI to isolate the conductors to the receptacle contacts from the conductors to the load if the line side wiring to the GFCI is improperly connected to the load side when the GFCI is in a tripped state. The trip portion operates independently of the circuit interrupting portion used to break the electrical continuity in one or more conductive paths in the device. The reset lockout portion prevents reestablishing electrical continuity of an open conductive path if the circuit interrupting portion is not operational or if an open neutral condition exists.
While the breaking of the electrical circuit and the utilization of bridge contacts provides electrical isolation protection between the load conductors and the receptacle contacts when the GFCI is in a tripped or non-conducting state, means which can prevent the prongs of a plug from being inserted into the receptacle of a GFCI when in a non-conducting state, either with or without the bridge contacts is desired to provide added user safety.
In one embodiment, the circuit interrupting device such as a GFCI includes phase and neutral conductive paths disposed at least partially within a housing between the line and load sides. The phase conductive path terminates at a first connection capable of being electrically connected to a source of electricity, a second connection capable of conducting electricity to at least one load and a third connection capable of conducting electricity to at least one user accessible load through a receptacle. Similarly, the neutral conductive path terminates at a first connection capable of being electrically connected to a source of electricity, a second connection capable of providing a neutral connection to the at least one load and a third connection capable of providing a neutral connection to the at least one user accessible load through the receptacle. The first and second connections can be screw terminals.
The GFCI also includes a circuit interrupting portion disposed within the housing and configured to cause electrical discontinuity in one or both of the phase and neutral conductive paths between the line side and the load side upon the occurrence of a predetermined condition. A reset portion activated by depressing a spring loaded reset button disposed at least partially within the housing is configured to reestablish electrical continuity in the open conductive paths. The reset button assumes a first or a second position which is determined by the conductive state of the GFCI. When the GFCI is in a conducting state, the reset button is substantially fully depressed within the housing of the GFCI, here referred to as a first position. When the GFCI is in a non-conducting state, the reset button projects outward beyond the top surface of the housing of the GFCI, here referred to as the second position.
The GFCI also includes a reset lockout that prevents reestablishing electrical continuity in either the phase or neutral conductive path, or both conductive paths if the circuit interrupting portion is not operating properly. Depression of the reset button causes at least a portion of the phase conductive path to contact at least one reset contact. When contact is made between the phase conductive path and the at least one reset contact the circuit interrupting portion is activated to disable the reset lockout portion and reestablish electrical continuity in the phase and neutral conductive paths.
The GFCI also includes a trip portion that operates independently of the circuit interrupting portion. The trip portion is disposed at least partially within the housing and is configured to cause electrical discontinuity in the phase and/or neutral conductive paths independently of the operation of the circuit interrupting portion. The trip portion includes a trip actuator, such as a button, accessible from the exterior of the housing and a trip arm preferably within the housing which extends from the trip actuator. The trip arm is configured to facilitate the mechanical breaking of electrical continuity in the phase and /or neutral conductive paths when the trip actuator is actuated.
Located within a GFCI device having a receptacle is a movable contact bearing arm which is held in either a closed or open position with a fixed contact by a latching member that is connected to the spring loaded reset button. The reset button assumes a first or a second position which is determined by the conductive state of the GFCI. When the GFC is in a conducting state, the reset button is substantially fully depressed within the housing of the GFCI. When the GFCI is in a non-conductive state, the reset button projects outward beyond the top surface of the housing of the GCFI. Thus, the movable contact bearing-arm, acting through a latching member, determines the position of the reset button. A blocking member located within the body of the GFCI is positioned by the reset button to allow free access of the prongs of a plug into the openings of the receptacle when the reset button is depressed or to block at least one opening of the receptacle to prevent a plug from entering the openings of the receptacle when the reset button projects out beyond the surface of the housing. Thus, when the GFCI is in a conducting state, the reset button is recessed within the GFCI housing and positions the blocking member to the first position to allow the prongs of a plug to be inserted into the receptacle openings. When the GFCI is in a non-conducting state, the reset button protrudes outward from the housing of the GFCI to position the blocking member to the second position to block at least one opening of the receptacle to prevent the prongs of a plug from entering the receptacle. GFCI""s normally have two separate sets of internally located contacts known as bridge contacts where one set is used to connect a load to the source of electricity and the second set is used to connect a user accessible load to the source of electricity. The bridge contacts provide isolation between the conductors to the load and the conductors to the contacts of the GFCI receptacle when the GFCI is in a fault state. In the GFCI here disclosed, the blocking member prevents the prongs of a plug from entering the receptacle when the GFCI is in a fault state and, therefore, can eliminate the need for the bridge contacts.